Retirement: Bulletproof Your Portfolio -- Which asset classes do the best in economic declines? Bonds often work well, but nothing beats diversification. Reviewing the recessions of the past 40 years.

AS AMERICA'S ECONOMIC MALAISE deepens, invest-ors can glean some insights by turning to the past.

In the six slumps in the past 40 years, which lasted an average of 11 months, long-term bonds were the most consistent performers, according to an analysis performed for Barron's by the Bespoke Investment Group of Harrison, N.Y. Treasuries with maturities of 10-years or longer gained an average of nearly 14% during the six downturns. But...